1. Field of the Invention
This invention relates to a method of manufacturing a rotor for a vane rotary compressor.
2. Description of the Prior Art
Conventionally, a rotor is manufactured by cutting a rotor material formed with vane slits, which is made by extruding aluminum powder.
More specifically, a billet is formed by subjecting an aluminum alloy powder to hot press, and the billet is heated to a temperature within a range of 350 to 450.degree. C. and fitted in a die heated to a temperature within a range of 300 to 400.degree. C., followed by shaping the billet into a rotor material by press. At this time point, the rotor material has only vane slits formed therein during the extrusion process. Thereafter, the rotor material is out to a predetermined length, and then a shaft hole is machined through a central portion of the rotor material, and oil grooves are formed on out surfaces of the same by end milling. Subsequently, a shaft is press-fitted in the shaft hole, and the grooves are subjected to finish machining.
In the above method, however, the rotor material is liable to be distorted or warped, so that it is difficult to ensure perpendicularity of each of the vane slits with respect to the end faces of the rotor. As a result, it is required to carry out an additional machining for achieving the perpendicularity.
Further, since the die and the material are not lubricated, a peripheral surface of the material galls or burns due to friction between the die and the material, which results in degraded accuracy of finishing. Moreover, it is required to carry out an additional operation for cutting the oil grooves after the rotor material is shaped, which leads to an increase in manufacturing costs of the rotor.